Nature and Science, 5(1), 2007, Huang and Wang, The Effects of 60Hz Magnetic Fields on Plant Growth The Effects of 60Hz Magnetic Fields on P lant Growth Hsin-Hsiung Huang 1* and Show-Ran Wang 1 1 Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, R.O.C. Telephone: (886) 2-27333141 Ext 7211 Fax: (886) 2-27376424 E-mail: [email protected]ABSTRACT: The biological effects of extremely low frequency magnetic fields (ELF MFs) on living organisms have been explored in many studies, but few of them investigate how different waveform MFs act upon their growth. In this study, the biological effects of both a 60Hz sinusoidal MF and a 60Hz pulsed MF on the early growth of plants are presented using mung beans as an example. The sinusoidal MF is produced using a specially-made circuit with a circular iron coil and a triac lamp in series which is driven by 110Vrms 60Hz AC power, and the pulsed MF is produced using the same equipment with the knob of the triac lamp adjusted manually. The results indicate that the 60Hz sinusoidal magnetic field has an enhancing effect on the ear ly growth of mung beans, however some morbid state phenomena were observed on the sprout roots. Also, the effect and morbidity rate increases with MF intensity. In contrast, the 60Hz pulsed magnetic field has a slightly inhibitory effect on mung bean growth. [Nature and Science. 2007;5(1):60-68]. Keywords:biological effect; coil; ELF MF; triac 1 Introduction As electric appliances such as TV, lights, fans, radiators, etc. are increasingly commonplace nowadays, the effects of the extremely low frequency magnetic field (ELF MF) produced by such equipment on the living organism are much more of concern. Most of the magnetic fields induced are of 60Hz sinusoidal waveform because 60Hz AC power is the most commonly used power rating all over the world. But there are many other occasions where the magnetic fields produced are in the form of a pulsed train. Therefore it is vitally important to find out whether there is any effect on living organisms resulting from exposure to either kind of MF. Several studies have suggested that ELF MFs may modify plant growth and development (Celestino, 1998; Davies, 1996; Picazo, 1999; Rapley, 1998; Smith, 1993, 1995; Stange, 2002), but exposure to magnetic fields induces quite a variety of biological effects and moreover, knowledge of the effects on living organisms is still not very clear. Nevertheless, the points of view described in (Lednev, 1991; Liboff, 1992) imply that an ELF MF may affect ions in cells, and can be described by the following equation: DCB m q fπ 2 = (1) where f is the frequency of the ELF MF (Hz), q/m is the charge-to-mass ratio of the ion(C/kg), B DC is the magnetic flux density of the static MF (T) that is superimposed on the ELF MF. From Eq. 1, it can be seen that the motion of ions is severely affected by f and B DC . In other words, different waveform magnetic field sources will result in varied biological effects on living organisms because their frequency spectrums are different. The present study aims to assess the effects of two different waveforms of magnetic field source (a 60Hz sinusoidal MF and a 60Hz pulsed MF) on plant growth using mung beans as test material, and attempts to relate the effects to the waveform spectrum of the magnetic fields. The sinusoidal MF is induced by a specially-designed electrical circuit which is driven by 110Vrms 60Hz AC power, and the 60Hz pulsed MF is produced from the same circuit, using the knob on the triac (two thyristors in inverse-parallel) for adjustment. Using the exposure system proposed in this paper, the MFs can be produced and mostly concentrated in the coil. Since the MF is concentrated, the affects of the MF on the personnel executing this experiment can be reduced. In the experiment, the exposed mung beans were grown in two places with different magnetic intensity, and additionally the control mung beans were grown in an ambient environment to observe any differences in biological effects on the growth of our test material. 60
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
ABSTRACT: The biological effects of extremely low frequency magnetic fields (ELF MFs) on livingorganisms have been explored in many studies, but few of them investigate how different waveform MFs
act upon their growth. In this study, the biological effects of both a 60Hz sinusoidal MF and a 60Hz pulsed
MF on the early growth of plants are presented using mung beans as an example. The sinusoidal MF is
produced using a specially-made circuit with a circular iron coil and a triac lamp in series which is driven
by 110Vrms 60Hz AC power, and the pulsed MF is produced using the same equipment with the knob of
the triac lamp adjusted manually. The results indicate that the 60Hz sinusoidal magnetic field has an
enhancing effect on the early growth of mung beans, however some morbid state phenomena were observedon the sprout roots. Also, the effect and morbidity rate increases with MF intensity. In contrast, the 60Hz
pulsed magnetic field has a slightly inhibitory effect on mung bean growth. [Nature and Science.
2007;5(1):60-68].
Keywords: biological effect; coil; ELF MF; triac
1 Introduction
As electric appliances such as TV, lights, fans, radiators, etc. are increasingly commonplacenowadays, the effects of the extremely low frequency magnetic field (ELF MF) produced by such
equipment on the living organism are much more of concern. Most of the magnetic fields induced are of
60Hz sinusoidal waveform because 60Hz AC power is the most commonly used power rating all over the
world. But there are many other occasions where the magnetic fields produced are in the form of a pulsed
train. Therefore it is vitally important to find out whether there is any effect on living organisms resulting
from exposure to either kind of MF.
Several studies have suggested that ELF MFs may modify plant growth and development (Celestino,
1998; Davies, 1996; Picazo, 1999; Rapley, 1998; Smith, 1993, 1995; Stange, 2002), but exposure to
magnetic fields induces quite a variety of biological effects and moreover, knowledge of the effects on
living organisms is still not very clear. Nevertheless, the points of view described in (Lednev, 1991; Liboff,
1992) imply that an ELF MF may affect ions in cells, and can be described by the following equation:
DC B
m
q f
π 2
= (1)
where f is the frequency of the ELF MF (Hz), q/m is the charge-to-mass ratio of the ion(C/kg), B DC is the
magnetic flux density of the static MF (T) that is superimposed on the ELF MF. From Eq. 1, it can be seen
that the motion of ions is severely affected by f and BDC. In other words, different waveform magnetic field
sources will result in varied biological effects on living organisms because their frequency spectrums are
different.
The present study aims to assess the effects of two different waveforms of magnetic field source (a
60Hz sinusoidal MF and a 60Hz pulsed MF) on plant growth using mung beans as test material, and
attempts to relate the effects to the waveform spectrum of the magnetic fields. The sinusoidal MF is
induced by a specially-designed electrical circuit which is driven by 110Vrms 60Hz AC power, and the
60Hz pulsed MF is produced from the same circuit, using the knob on the triac (two thyristors in
inverse-parallel) for adjustment. Using the exposure system proposed in this paper, the MFs can be
produced and mostly concentrated in the coil. Since the MF is concentrated, the affects of the MF on the
personnel executing this experiment can be reduced. In the experiment, the exposed mung beans were
grown in two places with different magnetic intensity, and additionally the control mung beans were grownin an ambient environment to observe any differences in biological effects on the growth of our test
Nature and Science, 5(1), 2007, Huang and Wang, The Effects of 60Hz Magnetic Fields on Plant Growth
61
2 Materials and Methods
2.1 Plant material Mung beans are used as the test material subject in this study, and two tests (one under a 60Hz
sinusoidal MF, and the other under a 60Hz pulsed MF) are implemented. In each test, beans of the same
weight (0.08g) and similar appearance are selected, and separated into three groups of 10, 30 & 30 beans.
Three groups are fertilized with distilled water with initial temperature of 31.5±0.5°C. Two groups of
them are grown in a magnetic field (exposed group 1 under higher magnetic intensity and exposed group 2
under lower magnetic field intensity), and the other group is placed in an ambient weak magnetic field(control). The reason only 10 beans are used in exposed group 1 is due to the limited space where they are
placed. The environmental conditions such as temperature, humidity and illumination of the three groups
of mung beans of two tests are maintained, as shown in Table 1.
TABLE 1 The temperature, humidity and illumination conditions in each group of the two tests
Sinusoidal MF Pulsed MFItem
Exposed 1 Exposed 2 Control Exposed 1 Exposed 2 Control
Nature and Science, 5(1), 2007, Huang and Wang, The Effects of 60Hz Magnetic Fields on Plant Growth
Figure 1. The complete set-up in this experiment
As shown in Figure1, the electrical power used to drive the circuit is 1ψ 110V 60Hz AC power. The
circular coil with outer diameter of 130mm and a 24mm air gap (cross section diameter = 28mm) is wound
100 turns with copper wire. The magnetic flux density (B) circulating in the iron core and air gap can betheoretically expressed in the following equations:
A A
g c
0µ µ +=
l l R
R
Ni B =
(2)
where R is total magnetic reluctance of the core and air gap, µ and µ 0 are the magnetic permeability of the
core and air respectively, A is the cross sectional area of the circular core, N is the number of turns of wire,
i is the current flowing through the wire and lc & lg are the core circumference and air gap distance,
respectively.
When the knob of the triac lamp is set to the high level position, the MF flowing in the iron coil is in a
60Hz sinusoidal form. However, when the knob is adjusted to the low level position, the MF producedshows as a pulsed train, as shown in Figure 2 and Figure 3. The locations of the three groups of mung beans
are shown in Figure 1. In order to confirm the magnetic flux density (B) in each position of two tests, a
magnetic meter is used to measure the B value at each position. These data are listed in Table 2.
Nature and Science, 5(1), 2007, Huang and Wang, The Effects of 60Hz Magnetic Fields on Plant Growth
Figure 2 The 60Hz sinusoidal magnetic field produced. Due to the poor quality power used and impedance
mismatching between the coil probe and oscilloscope (shown in Figure 1), the waveform of the MF does
not look like a perfect sine wave.
Figure 3. The 60Hz pulsed magnetic field induced
TABLE 2. The magnetic field intensities produced in each group of mung beans of the two tests
Test Exposed 1 Exposed 2 Control
Sinusoidal MF 235.0 µT 94.1 µT 0.17 µT
Pulsed MFa 11.1 µT 6.2 µT 0.20 µT
aThe pulsed MF intensities are measured using a magnetic meter which has limited bandwidth, so the peak
value will be higher.
3 Results
3.1 Water absorptionAfter 8 hours fertilization with distilled water, the three groups of mung beans were taken out to be
observed for germination and weighed. Exposed to the sinusoidal MF, the average weights of the mung beans in both the exposed 1 and exposed 2 groups were 0.180g, and the average weight of the control mung
beans was 0.140g. The weight ratio between the exposed and control mung beans was 1.29. This result
Nature and Science, 5(1), 2007, Huang and Wang, The Effects of 60Hz Magnetic Fields on Plant Growth
indicates that the mung beans that had been exposed to the sinusoidal MF had absorbed much more water
compared with the control mung beans. As for the other test exposed to the pulsed MF, the average weights
of the mung beans in both the exposed 1 and exposed 2 groups was 0.136g, and the average weight of the
control mung beans was 0.145g each. The weight ratio between the exposed and control mung beans was
0.94. This result shows that the mung beans that had been exposed to the pulsed MF had absorbed less
water compared with the control mung beans.
3.2 Early growth
The three groups of mung beans were then put back in their original positions for the remaining 16hours of the experiment. After they had been growing for 24 hours, the sprout diameter and length of the
mung beans in three groups were measured. For the test exposed to the sinusoidal MF, the distribution of
the sprout diameters of the three groups with 24 hours growth is sketched in Figure 4(a), and that of their
sprout lengths is shown in Figure 4(b). The statistical data are listed in Table 3. As shown, the average
sprout diameter and length of the mung beans in exposed group 1 were the greatest of all three groups, and
those of the mung beans grown in the ambient environment were the least. Therefore, a sinusoidal MF has
an enhancing effect on the early growth of mung beans, and the effect gets stronger as the MF intensityincreases.
(a)
(b)
Figure 4 (a) The sprout diameter distribution of the mung beans exposed to the sinusoidal MF. (b) The
sprout length distribution of the mung beans exposed to the sinusoidal MF. Both growth distributions
shift higher with increasing MF intensity. (There are 10 sample beans in exposed group 1, which is
less than the other groups because of limited space in the iron core airgap)